This invention pertains to fuel cell systems and, in particular, to gas cooler assemblies for use in fuel cell stacks.
In fuel cell stacks, it is common to provide some type of cooling mechanism for cooling the stack fuel cells. U.S. Pat. No. 4,192,906 discloses one type of cooling mechanism wherein plate structure is supported in the stack and defines a cooling passage for carrying a cooling gas. Procedures for fabricating the aforesaid plate structure have been devised wherein two plates are used, each plate being provided with a plurality of grooves. These plates are then situated in the stack with corresponding grooves in alignment to thereby define cooling channels of desired capacity.
In order to reduce stack height, it is also desirable to additionally provide in each plate opposite the surface containing the cooling grooves, a further set of grooves for use as process gas channels. Usually the process gas grooves of the two plates will carry different process gases, thereby necessitating that they be situated in transverse relationships relative to each other. It is further desirable to form the plates from carbonizable material as e.g., graphite/resin, in order to realize enhanced electrical and thermal conductivity.
In one approach used to fabricate cooling assemblies comprised of plates of this type, the plates are first carbonized and then joined together so as to align the corresponding cooling gas grooves. However, it has been found that due to the inherent differences in the plates, each plate undergoes a different degree of shrinkage during carbonization, thereby making alignment of the sets of cooling grooves extremely difficult. This situation is further aggravated by the existence of the process gas grooves in each plate and exact alignment is never fully achieved. As a result, the electrical conductivity of the assembly is undesirably reduced and the cooling gas flow undesirably modified.
It is therefore an object of the present invention to provide a cooling assembly which does not suffer from the disadvantages described above.